1. Field
Aspects of the present disclosure relate, in general, to position location and, more particularly, to modifying location related data during an ongoing data transfer session.
2. Background
It may be beneficial to obtain the location of a mobile device such as a wireless phone, laptop, tablet, identity tag etc., at one or more times and to provide the location to a client application or device for the purpose of supporting a service or function. Examples of services and functions include providing navigation instructions to the user of the mobile device; tracking and/or recording the location of some valuable asset; and enabling the mobile device to obtain its own location.
To support location of mobile devices that have the capability to access wireless networks such as Global System for Mobile Communications (GSM), Code Division Multiple Access (CDMA), Wideband CDMA (WCDMA), Long Term Evolution (LTE) and WiFi and/or fixed access networks such as packet cable and DSL, a number of position methods and associated positioning protocols have been developed that rely on communication between the mobile device and a location server supported by one or more intervening fixed and/or wireless networks. One such positioning protocol developed by the 3rd Generation Partnership Project (3GPP) in 3GPP Technical Specification (TS) 36.355 which is publicly available is known as the LTE Positioning Protocol (LPP) and is intended to locate mobile devices that are currently accessing an LTE network. An extension to this protocol known as LPP Extensions (LPPe) is being developed by the Open Mobile Alliance (OMA) to locate mobile devices that are currently accessing an LTE network or certain other kinds of network such as GSM, WCDMA, WiFi or fixed access. The relationship of LPPe to LPP is that each LPP message is allowed to optionally include an embedded LPPe message. An LPPe message not associated with an LPP message is not allowed. Since an LPPe message must be embedded inside an LPP message, procedures associated with LPPe messages must be associated with procedures for LPP messages which means that LPPe procedures can be the same as or extend LPP procedures but cannot conflict with LPP procedures which places constraints on what LPPe procedures can support.
The LPP, LPPe, and certain other positioning protocols support location by having the capability to transfer assistance data from the location server to the mobile device that is being located to better enable the mobile device to make measurements of suitable signals (e.g., signals from Global Positioning System (GPS) or Global Navigation Satellite System (GNSS) satellites, signals from wireless network base stations) and, in some cases, to determine its own location from these measurements. The protocols also have the capability to allow the location server to request and later receive particular signal measurements from the mobile device to enable the location server to calculate the location of the mobile device.
When the location of a mobile device is needed multiple times over a period of time, certain types of location related data, such as location assistance data and location measurement data may be sent periodically or when particular trigger conditions occur at a the mobile device or location server. In the case of LPP and LPPe, the assistance data will be related to a particular position method(s) defined in LPP and/or LPPe and may be delivered at periodic intervals. These intervals may be fixed and defined in the LPP or LPPe request for assistance data sent by a mobile target device to a location server or may be defined as being triggered by the occurrence of a particular event(s). Similarly, location information may be periodically delivered from a target device to a location server. Location information may contain information pertaining to location measurements and/or a location estimate for a target device. The periodic intervals of delivering the location information may be fixed or may be defined as being triggered by the occurrence of a particular event or events at the target device.
After the delivery of assistance data or location information has started, the receiver may not be able to modify the type of information being transferred or the conditions for periodically sending it without aborting and restarting the assistance data or location information transfer session. For example, a target device can send a request to a location server specifying particular assistance data that the server should transfer to the target either once only or periodically. But with existing positioning protocols such as LPP, the target cannot later send another request to the server to modify the type of assistance data to be transferred or the periodic intervals or trigger conditions for sending it. Similarly, a location server can send a request to a target device specifying particular location information the target should transfer to the server either once only or periodically. But with existing positioning protocols such as LPP, the server cannot later send another request to the target to modify the type of location information to be transferred or the periodicity or trigger conditions for sending it.
One procedure that would allow location related data (either assistance data or location information) to be modified would be to stop or abort an ongoing transfer and then start a new transfer that defines a new type of assistance data or new type of location information and new conditions for periodically sending the information. However, information and resources associated with the initial transfer may then be released when the initial transfer was stopped. Lost or missing information may need to be reacquired or re-obtained which could take a significant time period as well as requiring extra use of processing and signaling resources. More significantly, it may not be possible to re-obtain some information associated with the previous transfer. For example, in may not be possible to re-obtain any measurements related to previous locations of the mobile device or usefully provide assistance data to help enable previous location estimates for the mobile device. The consequences may include delay in effectively changing the periodic assistance data or location information and some loss of assistance data or location information.
Although modification of an ongoing assistance data or location information transfer procedure may confer benefits in terms of reducing delay and resource consumption and avoiding the unrecoverable loss of some assistance data or location information in comparison to a procedure that stop or aborts and later restarts the transfer, there may be problems in modifying the transfer. For example, if the receiver requests modification of the transfer, the receiver needs to be aware subsequently that the modification will be supported by the sender. Also the method for performing the modification may need to comply with preexisting rules associated with the positioning protocol being used to avoid either end aborting the transfer due to a perceived protocol error. Further, it may be beneficial to allow either the sender or the receiver to instigate the modification (e.g., the sender may need to be able to modify the data being transferred if the data available to it changes). Protocol support for the modification should thus ideally support these capabilities.
In the case of LPP, the protocol supports the requesting and subsequent transfer of either assistance data (from the location server to the target device) or location information such as location measurements (from the target device to the location server) but the protocol does not contain any means to modify a transfer once in progress. Although such a capability could be added to LPP, the resulting extended protocol might not be compatible with the previous version of LPP, meaning a device supporting the earlier version could not always interwork correctly with a device supporting the later version. In addition, if such a capability was added to LPPe (which extends LPP but does not modify LPP itself) it would have to be supported by existing LPP procedures which, as just mentioned, do not explicitly enable modification of an ongoing transfer. Therefore, the addition of a modification capability for assistance data or location information transfer becomes a problem to be solved.